>I have used VFP 6.0 to compile an old VFP 5 project. The resulting EXE was copied to a network drive and users are able to run the new EXE even though they only have VFP 5 runtime libraries on their workstations. How is this possible?
>

I've seen this with .APP files, but not .EXE files - the VFP6 runtime is able to run VFP5 executables, so the p-code for VFP5 commands should have remained the same. I'd guess that something else probably installed the VFP6 runtime without your knowledge in the past, since the executable looks for different runtime files during the startup.